Tonic contractions of the tensor tympani muscle: a key to some non-specific middle ear symptoms? Hypothesis and data from temporal bone experiments

Abstract

Conclusions. The results of this study show that in clinical practice it will not be easy to diagnose tonic contractions of the tensor tympani muscle and only a combination of findings will be helpful. Based on these experimental results a clinical study will be started which should clarify the diagnostic relevance of indicators of tonic tensor muscle contractions. Objectives. There are indications from the literature and from personal experience that tonic contractions of the tensor tympani muscle may play a role in some ear symptoms, such as fullness, certain cases of tinnitus, slight hearing loss or Ménière's disease-like findings. In order to prove this theory we looked for indicators, either visual or functional, to help clinically diagnose the functional state of the muscle, particularly its tonic contraction. Material and methods. Experiments simulating tensor contractions were carried out on temporal bone specimens. Traction was applied either to the isolated muscle, to its tendon or to the malleus neck. Effects were observed either visually via an endoscope or by impedance audiometry using multiple-frequency tympanometry. Results. During simulated tensor traction the aspect of the tympanic membrane changed slightly, i.e. there was some inward movement of the umbo. However, such effects were only identifiable during the pulling action or by directly comparing the “contracted” and “relaxed” states. Tympanometry revealed a decrease in the peak amplitudes and a shift in the middle ear resonance towards higher frequencies during contractions.